Effect of Sequence Distribution on Copolymer Interfacial Activity

• Published in: Macromolecules Vol. 38; no. 25; pp. 10494 - 10502
• Main Authors: Lefebvre, Michelle D, Dettmer, Christine M, McSwain, Rachel L, Xu, Chen, Davila, Jonathan R, Composto, Russell J, Nguyen, SonBinh T, Shull, Kenneth R
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 13-12-2005
• Subjects: Applied sciences; Copolymerization; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Preparation, kinetics, thermodynamics, mechanism and catalysts; Structure effect; Norbornene derivative copolymer; Experimental study; Complex catalyst copolymerization; Hydrogenation; Functional polymer; Saturated copolymer; Random copolymer; Chemical modification; Metathesis polymerization; Preparation; Diblock copolymer; Interface activity; Microstructure; Ring opening copolymerization
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma0509762

Interfacial segregation of diblock, gradient, and random copolymers was measured using forward recoil spectrometry. The polymers were synthesized by a ring-opening metathesis polymerization, allowing a high degree of control over the sequence distribution. The norbornene-based monomers have reactivity ratios close to unity, which makes them ideal for facile tailoring of different gradient copolymer profiles. The copolymers form a good weakly segregating model system for which we can obtain an estimate of the interaction parameter χ. Mean-field theory was used to describe the interfacial segregation results and to relate the measured quantities to the detailed molecular structure of the interface. The diblock copolymer forms a monolayer at the interface and significantly reduces the interfacial tension, while the random copolymer forms an interfacial wetting layer. The gradient copolymer exhibits intermediate behavior, forming a monolayer with a larger interfacial width than that of the diblock copolymer.